The present invention concerns a method of feeding substantially rectangular laundry articles to a laundry processing apparatus, such as an ironing roller, comprising aligning the rear edge of the laundry article to a predetermined angle with respect to the travelling direction on a conveyor plate, following which the laundry article is conveyed with the rear edge stretched, as well as an apparatus for performing the method.
These apparatuses are primarily used in big laundries in which they are used for smoothing and spreading large laundry articles, such as sheets, table-cloths, slips for eiderdowns, etc. for subsequent insertion of the laundry article into e.g. an ironing roller, it being important that these feeding devices spread and smoothen the laundry articles effectively so that undesired creases will not occur after the ironing roller. Most frequently, the laundry articles are inserted into the apparatus in that a laundry article is taken from a pile of laundry articles in a wrinkled state and optionally wet or damp, following which the laundry article is inserted into the machine, which subsequently processes the laundry article so that it can be transferred to e.g. an ironing roller in a spread and smoothened state.
Even though the laundry article is thus transferred to an optional ironing roller in a spread and smoothened state, unintentional creases in the laundry article may occur however after the ironing roller, if the laundry article is inserted askew into the ironing roller. These unintentional creases are produced in that, in this case, the ironing roller first pulls a corner of the laundry article forwardly, thereby forming wrinkles on the laundry article. It is therefore important e.g. in connection with such ironing rollers that the laundry article is oriented such that the entire one edge of the laundry article is moved into the ironing roller approximately in parallel with the axis of rotation of the ironing roller.
Therefore, feeders are frequently provided with a device capable of orienting the laundry article such that when inserted into a subsequent optional ironing roller the laundry article has the desired orientation.
Numerous proposals for the construction of devices capable of performing the above-mentioned processes are known today. Thus, EP patent application 266 820 discloses a feeder comprising a roller capable of rotating about its own axis, the laundry article being so positioned across said roller as to extend down on both sides of the roller. The laundry article will then frequently be disposed askew on the roller, which is therefore adapted so as to be twistable about its own longitudinal axis such that the laundry article may be aligned with respect to the roller. This alignment takes place by positioning the laundry article with respect to a plurality of optional sensors arranged in a horizontal plane, so that these can detect an edge on the part of the laundry article which hangs down on one side of the roller. The roller can then be rotated and twisted in sequence, so that the edge of the laundry article precisely covers the row of optical sensors, said laundry article having thereby been aligned with respect to the feed direction of the roller.
Further, EP patent application 424 290 discloses a feeder having a short and wide conveyor belt across which the laundry article is hung so as to hang down on each side of the conveyor belt. This feeder too has sensors detecting the position of the rear edge of the laundry article on the conveyor belt with a view to aligning the laundry article with respect to this conveyor belt. In this device, the alignment takes place by retaining the part of the laundry article hanging down on one side, while causing the laundry article to be moved with respect to the conveyor belt. This is effected by pressing an elongate rod toward the laundry article between the location where the laundry article is retained and the conveyor belt, whereby the laundry article is displaced on the conveyor belt, thereby making it possible to align the laundry article with respect to the conveyor belt.
In both of the above-mentioned devices the detection of the position of the laundry article takes place in the manner that the laundry article is first moved to and fro across the roller or the conveyor belt, until one of the outermost photocells is precisely covered or exposed with respect to the laundry article. Then there is a separate activity to align the laundry article, by twisting the roller or displace the laundry article across the conveyor belt, which stands still in this position. This process goes on until the rear edge of the laundry article is aligned with respect to the sensors, following which the laundry article is properly positioned on the roller as well as the conveyor belt. The roller or the conveyor belt is then started to advance the laundry article, which is then transferred to the subsequent laundry processing apparatus.
Even though these devices can thus align the laundry article fully automatically, they are vitiated by a serious drawback, because the above-mentioned processes cannot be performed with continuous feeding of the laundry article. In certain cases, it is even necessary for the laundry article to be conveyed rearwardly with respect to the direction of feed because of the necessity of initially positioning the rear edge of the laundry article opposite one of the sensors. In particular the feeder of EP patent application 424 290 requires that the conveyor belt stands still during the laundry article aligning process.
The object of the invention is to provide a method and an apparatus which make it possible to perform detection of the position of the laundry article rear edge as well as braking or alignment of the laundry article during the continued feeding of the laundry article.